function Person(name){
  this.name = name
}
Person.prototype.say = function(name){
  return this.name
}
Person('abc')
const a = new Person('abc').say.call({})
console.log(a)

var p = {
  x:'Y'
}
var fn = () =>{
  this.x = 'z'
}
fn.call(p)
console.log(p)